Bruce Merrifield's pioneering development of solid phase peptide synthesis created a useful process for synthesis peptide chains through its use of filtration to remove reagents between steps. The process has involved repetitive cycles which include coupling and deprotection with washing and filtration in-between each step (FIG. 1). It has commonly been assumed that washing is required between each step to completely remove the reagents previously used so that they don't undesirably participate in the next step. This typically involves “insertions” which refer to the incorporation of an extra amino acid. This is thought to occur through either residual base removing the protecting group (Fmoc) on an amino acid recently coupled thereby allowing a second amino acid to “insert”; or through residual activated amino acid left behind during the subsequent deprotection step which could couple to deblocked sites thereby “inserting” an extra amino acid from the previous step. It was recently shown, however, that washing after the coupling step was not required for the successful synthesis of peptides. In this work the coupling step was drained and the deprotection solution was subsequently added to the vessel (J. Collins, K. Porter, S. Singh and G. Vanier, “High-Efficiency Solid Phase Peptide Synthesis (HE-SPPS),” Org. Lett., vol. 16, pp. 940-943, 2014) (FIG. 2).